This is a comprehensive longitudinal study of the use and abuse of drugs and alcohol in a sample of 135 Hyperkinetic/MBD boys who were (a) seen for outpatient psychiatric evaluation in the five-year period between 1967 and 1972; (b) subsequently treated with a CNS stimulant drug (methylphenidate); and (c) followed up at adolescence by the present investigator with an extensive battery of tests, interviews, questionnaires, forms, and ratings (Loney, Langhorne, Paternite, Whaley-Klahn, Broeker & Hacker, 1976). In the first stage of the proposed study, data will be drawn from a multivariate computer archive maintained on these boys, and a series of questions about the prevalence of substance use will be investigated. Predictors of adolescent drug and alcohol use and abuse will also be identified, and the covariation of alcohol use, drug use, and other norm-violating and illegal acts (e.g., aggression and delinquent behaviors) will be determined. In the second stage of the proposed study, an additional sample of 100 Hyperkinetic/MBD boys will be followed up at adolescence. These will be boys who were seen for outpatient psychiatric evaluation in the five-year period between 1972 and 1977 but who were not treated with a CNS stimulant. They will be matched with the 135 methylphenidate treated boys on the basis of age, IQ, and socioeconomic status, as well as on kind and severity of hyperkinetic symptoms. Prevalence of drug and alcohol abuse in the drug-treated and in the untreated hyperkinetic samples will then be determined and compared with data from normal groups. It is anticipated that data collection, coding, and storage; statistical analysis; and dissemination will take place throughout each of the three years of this study.